It is believed that some fuel injectors include features that reduce undesirable noise associated with operation of the fuel injector. For example, it has been known to locate a silencing chamber around the outlet end of the fuel injector. But this is believed to address noise caused by the expansion of gaseous fuel, not noise propagated by the actuator.
It is also known to provide a noise insulator formed in or around the fuel injector to prevent transmission of noise from the fuel injector. In one example, annular dampening elements also have been included as part of the fuel injector nozzle body, but at the fuel-metering section of the armature such that it is believed to be difficult to install, particularly post-manufacturing.
Another known example provides for a sound-dampening element formed unitarily as part of a fuel filter. The sound-dampening element, however, is believed to absorb noise propagating between the fuel injector and a fuel rail instead of damping the structure to reduce the vibration or noise.